The present invention relates to a sheet for picking off microorganisms from a surface and to a procedure for identifying or determining the presence of microorganisms using this sheet.
Pick-off culture media are used for the identification of microorganisms on surfaces, for example, on walls and on and in equipment, furniture, apparatus, fittings, installations, etc. These culture media usually consist of a layer of an aqueous culture medium jelly, usually based on agar-agar, on a suitable support. German Auslegeschrift 1,013,837 discloses, for example, absorbent supports, such as paper, textile fabric or plastics having a porous structure, as culture medium supports which are used for picking off microorganisms. To use these devices, the support provided with the culture medium, which is kept moist, is pressed against the surface to be tested. It is then removed and incubated at a suitable temperature until the microorganisms have become visible as colonies.
The known pick-off culture media have, however, a number of disadvantages. Moist culture media have only a limited stability and require special storage conditions. The pick-off operation on surfaces which are sensitive to moisture or on surfaces which withdraw water from the moist culture medium is problematical. Moreover, there is a high probability that microorganisms will not be taken up, or at least will not be take up in a sufficient amount, upon simply being brought into contact with a moist medium.